Sound only coming from Front Tweeters and Rear speakers

[Mike534x]

So this has been bugging me for awhile now, and I finally want to address it with the free time I have. When I purchased the TB it came with the factory Bose HU, at the time it appeared that all the speakers were working correctly. About a week into owning it, we had the Pioneer AVH-X3600BHS radio I originally purchased for our other TB installed into this one. I know the radio worked fine with the setup in the other TB (it had the non-Bose setup). Since then, it started bugging me how the sound up front only comes out of the tweeters in the dashboard, when putting your ear up to the front speakers on both the driver and passenger side doors, you can hear sound but its very light and faint. I figured the factory Bose speakers were on their last legs and went out and purchased 2 sets of Kenwood KFC-1665S, I've got them installed up front with no noticeable difference and I have yet to install the rear ones.

Funny enough, the rear speakers do have sound, I had to go into the HU and change what I think were the balance settings and had it centered just a touch or too to the rear to get the sound evened out with the front. I've tried changing several things in the radio that hasn't helped much, there isn't much base either. Which makes me wonder if the factory Bose amp isn't wired/connect or whatever with the HU. I'm not an audio expert, so correct me if I'm wrong, but would the amp have any effect on the way the sound is channeled to the speakers or is this controlled through the HU? I'm just taking shots in the dark here, I was gonna pick up a PAC RP5-GM11 to regain the steering wheel controls and retained accessory feature, and know it was listed for the Bose system so I thought maybe it played a part in it somehow.

If anyone has any ideas I'm all ears, mostly hate the "emptiness" from not having fill-in sound from the doors, while the tweeters bounce everything off the windshield.

 

[Mooseman]

If the current interface you have isn't specifically for Bose systems, then it could cause the issues you are having. You also can't use the fader with this system. The RP5-GM11 will work with this setup.

 

[Mike534x]

If the current interface you have isn't specifically for Bose systems, then it could cause the issues you are having. You also can't use the fader with this system. The RP5-GM11 will work with this setup.

Thanks Mooseman . I didn't do the install, but from what I'm aware, it was just hooked up with a regular wiring harness. I would do the job myself, but I'm afraid of botching up the wiring. Yep fader was the word I was looking for, I figured the wiring for the amp would of been part of the harness going to radio without the need of the PAC module.

 

[littleblazer]

Iirc the feed for the tweeters is the same as the front woofers, the bose amp splits it into highs and lows from the signal internally. Maybe there is a fault in the amp section? Maybe a crossover setting on the head unit?

 

[Matt]

Speaking of crossovers, the Bose amp has the crossovers in it rather than using crossovers in a component speaker system.

 

[Mike534x]

Iirc the feed for the tweeters is the same as the front woofers, the bose amp splits it into highs and lows from the signal internally. Maybe there is a fault in the amp section? Maybe a crossover setting on the head unit?

I'll give the settings another look over, I think I've explored and tried all the options. I'm positive the front speakers were working with the factory HU before swapping it with the Pioneer. If it is an issue with the amp, how hard are they to change out and wire up for a novice?

 

[Matt]

If you're changing it out for another Bose amp, should be plug and play.

 

[Mike534x]

If you're changing it out for another Bose amp, should be plug and play.

I was debating about doing that as a last ditch effort in case the PAC module doesn't solve it. I spent a good chunk of time playing/changing every audio setting and it still sounds like the front speakers are muffled/low. After doing some quick pricing, it seems like it'd be more cost efficient to go with an entirely new amp given how pricey the Bose one is after searching online.

 

[Mooseman]

Could probably find one cheap in a pick-a-part. If it does the same thing, then it's something else.

There's also a possibility that the speakers themselves are bad. I've had a couple of tweeters go on me and picked up some replacements at the pick-a-part.

 

[Mike534x]

Could probably find one cheap in a pick-a-part. If it does the same thing, then it's something else.

There's also a possibility that the speakers themselves are bad. I've had a couple of tweeters go on me and picked up some replacements at the pick-a-part.

Didn't think of that. What are the odds of both of the speakers being bad, they're roughly only 6 months old. Granted, the sound was still low/muffled when I put them in. I do have the set that was supposed to go into the rear doors I could try swapping in and see if it makes a difference. Funny enough there is a pick-a-part literally 5 minutes down the street, each time I've paid them a visit they never seem to have any SWB/LWB TB/Envoys.

I do have it scheduled to go into the shop that installed the radio to have the PAC wired in, so we'll see what happens, would be great if it was because of the amp needing the module to work.

 

[littleblazer]

Hey, I was just looking through the service manuals, you happen to remember if the truck had noise reduction on the oem radio?

 

[Matt]

I was debating about doing that as a last ditch effort in case the PAC module doesn't solve it. I spent a good chunk of time playing/changing every audio setting and it still sounds like the front speakers are muffled/low. After doing some quick pricing, it seems like it'd be more cost efficient to go with an entirely new amp given how pricey the Bose one is after searching online.

If you put an entirely new aftermarket amp in, then you'll need to rewire everything instead of using the factory wiring for the amp and speakers.

 

[Mike534x]

Hey, I was just looking through the service manuals, you happen to remember if the truck had noise reduction on the oem radio?

I honestly don't know, wasn't even aware it had a noise reduction function. It had the 6 disc CD changer, is there an RPO code to tell if it had it? I can post mine if it helps.

If you put an entirely new aftermarket amp in, then you'll need to rewire everything instead of using the factory wiring for the amp and speakers.

Darn, kind of figured some rewiring was going to be involved somehow. I'll stick to the easier/cheaper options.

 

[littleblazer]

I honestly don't know, wasn't even aware it had a noise reduction function. It had the 6 disc CD changer, is there an RPO code to tell if it had it? I can post mine if it helps.



Darn, kind of figured some rewiring was going to be involved somehow. I'll stick to the easier/cheaper options.

Think there is a microphone on the ceiling... I don't think it's an issue because it should do all equally... sorry thought I was on to something.

 

[budwich]

I suspect it is more than likely that without the PAC module in place, you are not going to get a functional system. Not sure how someone could wire up things correctly without it.... certainly a question for the "installer".

 

[Matt]

Think there is a microphone on the ceiling... I don't think it's an issue because it should do all equally... sorry thought I was on to something.

The mike is for the voice recorder, if it has one. Also, AKAIK, there's no noise reduction feature on the OEM radio...at least I haven't seen one in the 10 years I've owned the truck.

 

[littleblazer]

The mike is for the voice recorder, if it has one. Also, AKAIK, there's no noise reduction feature on the OEM radio...at least I haven't seen one in the 10 years I've owned the truck.

I don't know, I saw this in one of the manuals, I don't recall it being available either but it is listed. Maybe later models?

 

[budwich]

there is some form of "noise compensation"... but its more for "volume increase (decrease) at speed" to overcome noise... but maybe its driven by mic as opposed to "speed feedback". I think its set in the DIC.

PS correction... its "auto volume" in radio settings.

 

[Mike534x]

Think there is a microphone on the ceiling... I don't think it's an issue because it should do all equally... sorry thought I was on to something.

I checked, it doesn't have the microphone. Well except the one going to the radio.

I suspect it is more than likely that without the PAC module in place, you are not going to get a functional system. Not sure how someone could wire up things correctly without it.... certainly a question for the "installer".

That is what I'm hoping. It just seems bizarre that the PAC module is needed to just get the amp to work, instead of just wiring it with the harness.

The mike is for the voice recorder, if it has one. Also, AKAIK, there's no noise reduction feature on the OEM radio...at least I haven't seen one in the 10 years I've owned the truck.

Small update:

I pulled the front passenger side door panel off to re-check the wiring to the speaker, figured there was no harm in seeing if maybe it wiggled out of place. I pulled out the new speakers that were going to be put into the rear doors, new speakers do the same thing. There is sound, but now that I have my ear closer to it, its more a "low" hum/with muffled sound if that makes sense. Curiosity got the better of me and decided to try to the speakers in the rear door, well, I hooked up the new speaker, no sound. Hooked up the factory Bose speaker and there is no sound at all coming from it, it did work prior to removing it. Not sure what happened, I did have the battery disconnected, but there is still sound from the Left rear door, and the tweeters, and the front doors if the "low" humming counts.

 

[littleblazer]

I checked, it doesn't have the microphone. Well except the one going to the radio.



That is what I'm hoping. It just seems bizarre that the PAC module is needed to just get the amp to work, instead of just wiring it with the harness.




Small update:

I pulled the front passenger side door panel off to re-check the wiring to the speaker, figured there was no harm in seeing if maybe it wiggled out of place. I pulled out the new speakers that were going to be put into the rear doors, new speakers do the same thing. There is sound, but now that I have my ear closer to it, its more a "low" hum/with muffled sound if that makes sense. Curiosity got the better of me and decided to try to the speakers in the rear door, well, I hooked up the new speaker, no sound. Hooked up the factory Bose speaker and there is no sound at all coming from it, it did work prior to removing it. Not sure what happened, I did have the battery disconnected, but there is still sound from the Left rear door, and the tweeters, and the front doors if the "low" humming counts.

That sounds like something is blowing the outputs on the amp or it's going into protection of some sorts... That isn't good I think...

 

[Mike534x]

That sounds like something is blowing the outputs on the amp or it's going into protection of some sorts... That isn't good I think...

Agh. I really hope I didn't just lose the output on the AMP.

 

[littleblazer]

Agh. I really hope I didn't just lose the output on the AMP.

You're saying it was working, then you swapped the speakers and it stopped, and you then put back the factory speaker and it's not working now?

 

[Mike534x]

You're saying it was working, then you swapped the speakers and it stopped, and you then put back the factory speaker and it's not working now?

Yeah. It's weird honestly, back in January the rear driver side speaker did the same thing. Figured it was dead so I used my then work discount to buy the speakers for the front and rear. Took it all apart when I realized the mounting brackets were incompatible, re-connected the factory speaker and it was working again. Thought it was corrosion on the connectors but they appear to be fine.

 

[budwich]

I think some of the "control lines" cause muting in the amp at certain times. Again, how is the "non GM" unit wired? You will likely find your answer. To me, it sounds like your HU is "pushing" a non-powered amp section (for what ever reason).

 

[Mike534x]

I think some of the "control lines" cause muting in the amp at certain times. Again, how is the "non GM" unit wired? You will likely find your answer. To me, it sounds like your HU is "pushing" a non-powered amp section (for what ever reason).

I'm not sure. I can try popping off the trim tomorrow, pull the HU out and take a picture of how it's currently wired. Would this really cause the speaker to just lose sound entirely after trying to swap it? I've never come across an issue like this before.

 

[Mike534x]

Update 2:

Got back from the guy that does our installs. He claims the problem lies with the amp, because of the low-hum/muffled sound coming from the front doors. He thinks there is blown capacitors that are back feeding (or something similar along those lines) causing an issue with the power output going to the speakers. I asked about going just aftermarket and I could tell he didn't seem keen on running new wiring and putting a different amp in, and because the vehicle is too "old" to put that kind of money into. He suggested I just replace the current factory Bose one, or bypass it. He doesn't believe the PAC module will do anything, even though it says it retains the factory amp.

 

[littleblazer]

You still have the original head unit?

 

[Mike534x]

Yep, it's somewhere out in the garage.

 

[littleblazer]

If it still works, why don't you swap it in and check for function. if everything checks out then, you need the module. It would eliminate any faults with the install though

 

[Mike534x]

Oh that's a good idea! I didn't even think of swapping in the factory unit, I did manage to find it after some digging, will be putting it in tomorrow. Fortunately it'll be warm, and good timing to pull my cluster again.

 

[Mike534x]

I swapped in the stock radio, same results. I'm assuming the problem lies in the amp at this point?

 

[budwich]

make sure power is getting to the amp and of course, that there is a ground also.

 

[littleblazer]

I would say so. Next thing to do would be test inputs and outputs at the amp. There is a link for the service manuals here so you can get the pin outs. the image I linked a couple posts back should be the output. But I fear it is internal because the input for the front stage is shared to the amp where it is internally split to the tweeters and woofer. It could be simple though.

 

[Mike534x]

I would say so. Next thing to do would be test inputs and outputs at the amp. There is a link for the service manuals here so you can get the pin outs. the image I linked a couple posts back should be the output. But I fear it is internal because the input for the front stage is shared to the amp where it is internally split to the tweeters and woofer. It could be simple though.

I'll try taking a multimeter to it soon hopefully, its been cold out and I didn't want to risk cracking the plastic panel attempting to pull it off.

I did some searching on here and the old old site and found some interesting information, mostly pertaining to the Bose systems configuration that seems to have been left unresolved sort of.

What I gathered was that the Bose setup is split so the tweeters act as the highs, front doors as lows and rears as mids. It appears that when you replace the factory speakers with aftermarket ones the volume is low/humming like, which is what I'm experiencing. It doesn't seem to happen to any of the SWB/LWB without the Bose system or if they have the non lux amp. The only solutions seem to be if you put the factory speakers back in as a replacement or gut the system entirely and put an aftermarket amp and setup in place.

The posts were mainly with the stock HU and not an aftermarket which is more odd, so I'm really curious to see if the module helps correct it, but I doubt it'll change much. Another was that the speakers need to be the same ohm as the factory ones and I believe the fronts were 2 ohm and the rears are supposedly rated at 4 ohm. The ones I bought are rated to run at 4, so they should in theory work with the rear doors. I was debating about getting a cheap set of 2 ohm speakers to place in the front doors just to see what would happen. It's an odd system, and a lot of different information posted about how it works and what not. It seems like my problem falls into a mix of what others experienced and now I'm determined to find a resolution to it.

 

[Mike534x]

Update #3

Well I got everything installed yesterday, there is a very small improvement coming from the front door speakers. I haven't had a chance to mess around with the sound settings in the new HU yet, but there is a small amount of sound being projected out of the speakers (the humming is still present, but has gone almost away so there is progress being made). I'm going to pick up a cheap set from either Best Buy or Walmart with a 2 ohm rating to see if they fully come back to life. So far, the PAC module is functioning, On-Star, chimes, and RAP are working. The installer checked the power going to the doors, both speakers are receiving power. It looks like the channel that feeds to the rear passenger door from the Bose amp has blown/failed. I'm not still not sure how the channel blew, the rear's are supposedly rated at 4 ohm's, and the speakers I connected are rated for 4, I'm going to try one more time with a different speaker, if not, I'll replace the amp and be done with it.